Patients with Thyroid Eye Disease (also called Graves’ Disease) develop bulging of the eyes and retraction of the eyelids. This causes increased exposure of the eye, leading to dryness, redness, irritation, and discomfort. Severe exposure can cause scarring and damage to the cornea, which is the clear covering of the eye.
Patients with Thyroid Eye Disease also develop double vision because eye movements become limited and the eyes become misaligned. In severe cases of Thyroid Eye Disease, there can be visual loss from damage to the optic nerve (the cable connecting the eye to the brain).
What causes Thyroid Eye Disease?
Thyroid Eye Disease is an autoimmune condition, which means that the body’s immune system mistakenly targets its own tissues. The immune system’s attack on the muscles that move the eye causes them to thicken and become stiff. As a result, these muscles cannot properly move the eye to all of its positions. In addition, these changes cause the eyeball to push forward and the eyelids to pull backward. This bulging of the eyeball is called “proptosis.”
In many (but not all) patients with Thyroid Eye Disease, this autoimmune process also affects the thyroid gland, causing it to function either too much or too little. Cigarette smoking increases the risk of developing Thyroid Eye Disease.
How is Thyroid Eye Disease diagnosed?
The doctor will diagnose Thyroid Eye Disease based on symptoms and the results of the examination and diagnostic tests. The examination may show that the eye movements are limited because particular eye muscles are affected. In addition, the doctor will measure the amount of misalignment between the eyes. The amount of eye bulging is measured. It is important to check if there is any visual loss. Often the doctor will order an MRI or CT scan of the brain and orbits. In patients with Thyroid Eye Disease, this test will show which muscles are affected and exclude other conditions. Finally, the doctor will check blood work, especially to see if there are thyroid abnormalities in addition to eye problems. Problems of the thyroid gland require the attention of an endocrinologist.
What are the treatments for Thyroid Eye Disease?
There are three main ways to treat the double vision that is caused by Thyroid Eye Disease. Prisms can be used with eyeglasses to try to reduce double vision. Patching one eye will eliminate double vision, but this is not a satisfactory solution for many patients. Finally, misalignment of the eyes can often be improved with surgery. In order to maximize the chance that surgery will successfully realign the eyes, typically the doctor will recommend waiting until the amount of misalignment has remained stable for approximately six months.
It is important to use lubricating eye drops and ointments to prevent dryness and injury to the surface of the eye. Other medications have limited benefits in treating Thyroid Eye Disease. One clinical study found that selenium (an anti-oxidant mineral) improved many symptoms when the condition is mild. Corticosteroids (such as Prednisone) can occasionally improve eye movements. However, for most patients there are no convincing long-term benefits from this medication.
When necessary, an additional operation can be performed to relieve severe eye bulging by making more space in the orbit. In addition, surgery can be done to correct the position of the eyelid, which is an important aspect of keeping the eye properly lubricated. Radiation therapy is used when sight is threatened in severe cases of Thyroid Eye Disease. Visual loss can occur when the optic nerve (the cable that connects the eye to the brain) is compressed by swollen, thickened eye muscles.
What is the prognosis for patients with Thyroid Eye Disease?
The prognosis for patients with Thyroid Eye Disease is quite variable. Some patients have a very mild course and do not require treatments other than eye lubrication. Other patients have eye misalignment causing double vision, and may ultimately require eye surgery. A minority of patients have an extremely severe form of this disease that can cause loss of vision, and they require urgent treatment with medications, radiation treatment, and/or surgery.
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